Loosely coupled environments are computer system complexes that comprise of a number of processors that share data storage and communications networks. Each complex, however, retains its own dedicated memory which is not usually shared between such complexes. Each processor in the environment can access all data on the shared databases and can run any application program stored in the data storage. This allows the presentation of a single image to the remote host or user and allows workload balancing by the processor complexes. The remote host or user does not care which of the coupled processors executes the application, allowing more effective workload balancing without operator or end user action.
Data processing systems are employed within loosely coupled environments to maintain data needed in different locations throughout the environment to service the processing of different applications. The data may be maintained in one or more host systems linked to the remote hosts and to other host systems forming a network of communication links in the environment. In order to send messages from one host on the link to another host on the link, communication rules called protocols are established to control the communication by routing messages and accessing appropriate host computers on the link in the complex or the environment. These communications protocols typically exists as part of a teleprocessing architecture that defines the function and structure of data communications products.
When a remote host sets up communication with a host in order to request processing of an application, extensive time and effort goes into setting up the communication link since the remote host has to be associated with the host carrying the application through the passing of certain information including the appropriate communication protocol. If the host then is unable to complete the processing of the application because of a subsequent outage, a failure or some sort of an error condition detected by the environment, the remote host has to duplicate the initial effort spent in setting communication with the now failing host in order to establish a second communication link with a replacement host. Furthermore, the need to re-established a new connection, will cause loss of data that had been sent previously over the pre-existing connection between the remote host and the now failing host.